This invention concerns novel fragrance compounds, and perfumes and perfumed products comprising the novel compounds.
In one aspect, the present invention provides a compound having the structure 
where R1 is a lower alkyl group, R 2, R3, R4 and R5 is each independently hydrogen or a lower alkyl group, R6 is hydrogen, a lower alkyl group, an alkylidene group or a lower alkenyl group and R7 is hydrogen or a lower alkyl group.
For brevity and simplicity, such materials will be referred to as xe2x80x9cthe compoundxe2x80x9d, xe2x80x9cthe novel compoundxe2x80x9d or xe2x80x9cthe compound of the inventionxe2x80x9d.
The compounds of the invention may exist in a number of isomeric forms, and the invention includes within its scope each individual isomer and also mixtures of isomers.
The term xe2x80x9clower alkylxe2x80x9d is used in this specification to mean an alkyl group having from 1 to 4 carbon atoms.
The term xe2x80x9clower alkenylxe2x80x9d is used in this specification to mean an alkenyl group having from 1 to 4 carbon atoms.
The compounds of the invention can possess fragrance or odour properties which are generally regarded as interesting, pleasant or attractive.
The currently preferred compound in accordance with the invention has R1, R2, R5, R6 and R7=CH3; R3 and R4=H, with a double bond in the ring at the 34 position. This compound thus has the structure 
and is 2-methyl-1-(1,2,4-trimethyl-3-cyclohexen-1-yl)-1-propanol. For brevity this compound is referred to herein as compound 1. Compound 1 has desirable odour properties, generally of a blackcurrant, green, buchu, cassis nature, and appears to have good substantivity. The compound also has good performance against kitchen malodour. Materials having cassis odour are of great interest to the fragrance industry, with such materials, eg Neocaspirene (described in U.S. Pat. No. 4537702), generally being of high value. Naturally occurring materials with cassis odour contain sulphur and the commonest synthetic materials with cassis odour contain sulphur or oximes. Compounds of the invention thus have the advantage of lacking sulphur or oximes. Compounds of the invention also constitute the first known alcohols having cassis odour.
Further compounds of the invention include the following:
The odour properties of the compounds of the invention mean that a compound or mixture of compounds in accordance with the invention may be used as such to impart, strengthen or improve the odour of a wide variety of products, or may be used as a component of a perfume (or fragrance composition) to contribute its odour character to the overall odour of such perfume. The compounds are stable and substantive. For the purposes of this invention a perfume is intended to mean a mixture of fragrance materials, if desired mixed with or dissolved in a suitable solvent or mixed with a solid substrate, which is used to impart a desired odour to the skin, hair and/or product for which an agreeable odour is indispensable or desirable. Example of such products are: fabric washing powders, washing liquids, fabric softeners and other fabric care products; detergents and household cleaning, scouring and disinfection products; air fresheners, room sprays and pomanders; soaps, bath and shower gels, shampoos, hair conditioners and other personal cleansing products; cosmetics such as creams, ointments, toilet waters, preshave, aftershave, body, skin and other lotions, talcum powders, body deodorants and antiperspirants, etc.
Other fragrance materials which can be advantageously combined with one or more compounds according to the invention in a perfume are, for example, natural products such as extracts, essential oils, absolutes, resinoids, resins, concretes etc., but also synthetic materials such as hydrocarbons, alcohols, aldehydes, ketones, ethers, acids, esters, acetals, ketals, nitrites, etc., including saturated and unsaturated compounds, aliphatic, carbocyclic, and heterocyclic compounds.
Such fragrance materials are mentioned, for example, in S. Arctander, Perfume and Flavor Chemicals (Montclair, NJ., 1969), in S. Arctander, perfume and Flavor Materials of Natural Origin (Elizabeth, N.J., 1960) and in xe2x80x9cFlavor and Fragrance Materialsxe2x80x941991xe2x80x9d, Allured Publishing Co. Wheaton, Ill. USA.
Examples of fragrance materials which can be used in combination with one or more compounds according to the invention are: geraniol, geranyl acetate, linalol, linalyl acetate, tetrahydrolinalol, citronellol, citronellyl acetate, dihydromyrcenol, dihydromyrcenyl acetate, tetrahydromyrcenol, terpineol, terpinyl acetate, nopol, nopyl acetate, 2-phenyl-ethanol, 2-phenylethyl acetate, benzyl alcohol, benzyl acetate, benzyl salicylate, styrallyl acetate, benzyl benzoate, amyl salicylate, dimethylbenzylcarbinol, trichloromethylphenylcarbinyl acetate, p-tert-butylcyclohexyl acetate, isononyl acetate, vetiveryl acetate, vetiverol, xcex1-hexylcinnamaldehyde, 2-methyl-3p-tert-butylphenyl)propanal, 2-methyl-3-(p-isopropylphenyl)propanal, 2-(p-tert-butylphenyl)-propanal, 2,4-dimethyl-cyclohex-3-enyl-carboxaldehyde, tricyclodecenyl acetate, tricyclodecenyl propionate, 4(4-hydroxy-4-methylpentyl)-3-cyclohexenecarboxyaldehyde, 4-(4-methyl-3-pentenyl)-3-cyclohexenecarboxaldehyde, 4-acetoxy-3-pentyl-tetrahydropyran, 3-carboxymethyl-2-pentylcyclopentane, 2-n-heptylcyclopentanone, 3-methyl-2-pentyl-2-cyclopentenone, n-decanal, n-dodecanal, 9decen-1-ol, phenoxyethyl isobutyrate, phenylacetaldehyde dimethyl acetal, phenylacetaldehyde diethyl acetal, geranyl nitrile, citronellyl nitrile, cedryl acetate, 3-isocamphylcyclohexanol, cedryl methyl ether, isolongifolanone, aubepine nitrile, aubepine, heliotropin, coumarin, eugenol, vanillin, diphenyl oxide, hydroxycitronellal, ionones, methylionones, isomethylionones, irones, cis-3-hexenol and esters thereof, indan musks, tetralin musks, isochroman musks, macrocyclic ketones, macrolactone musks, ethylene brassylate.
Solvents which can be used for perfumes which contain a compound according to the invention are, for example: ethanol, isopropanol, diethyleneglycol monoethyl ether, dipropylene glycol, diethyl phthalate, triethyl citrate, isopropyl myristate, etc.
The quantities in which one or more compounds according to the invention can be used in perfumes or in products to be perfumed may vary within wide limits and depend, inter alia, on the nature of the product, on the nature and the quantity of the other components of the perfume in which the compound is used and on the olfactive effect desired. It is therefore only possible to specify wide limits, which, however, provide sufficient information for the specialist in the art to be able to use a compound according to the invention, for his specific purpose. Typically, a perfume comprises one or more compounds in accordance with the invention in an olfactively effective amount. In perfumes an amount of at least 0.01% by weight or more of a compound according to the invention will generally have a clearly perceptible olfactive effect. Preferably the amount is in the range 0.1 to 80% by weight, more preferably at least 1%. The amount of the compound according to the invention present in products will generally be at least 10 ppm by weight, preferably at least 100 ppm, more preferably at least 1000 ppm. However, levels of up to about 20% by weight may be used in particular cases, depending on the product to be perfumed.
In a further aspect the invention provides a perfume comprising one or more compounds of the invention in an olfactively effective amount.
The invention also covers a perfumed product comprising one or more compounds of the invention.
The compounds of the invention may be synthesised by reaction of an appropriate aldehyde with a Grignard reagent to give a substituted alcohol. For example, compound 1 can be prepared by reaction of 1,2,4-trimethyl-3-cyclohexene-1-carboxaldehyde with isopropylmagnesium bromide or isopropylmagnesium chloride, as follows 
In a further aspect of the invention there is thus provided a method of making a compound in accordance with the invention, comprising a Grignard reaction of the aldehyde.
The aldehyde may be prepared via Diels-Alder chemistry. For example, 1,2,4-trimethyl-3-cyclohexene-1-carboxaldehyde can be prepared by reaction between 2-methyl-1,3-pentadiene and methacrolein (the latter conveniently being produced by Mannich chemistry).
The compounds of the invention may alternatively be synthesised by reduction of the corresponding ketone. For example, compound 1 can be prepared by reduction of 2-methyl-1-(1,2,4-trimethyl-3-cyclohexen-1-yl)-1-propanone (referred to for simplicity as molecule A), eg using lithium aluminium hydride in ether, as follows 
A further aspect of the invention is thus a method of making a compound in accordance with the invention, comprising reduction of a ketone.
The corresponding ketone may be prepared by reaction of an appropriate diene and dieneophile in a Diels-Alder reaction. For example, molecule A may be produced by Diels-Alder reaction of 2-methyl-1,3-pentadiene and 2,4-dimethyl-1-penten-3-one (also referred to herein for convenience as molecule B), as follows 
The Diels-Alder reaction may be performed in known manner and is preferably carried out as a thermal reaction, with the reactants heated together to obtain addition as the temperature rises, or under pressure, with the reactants being heated together in an autoclave or a pressurised plug flow reactor.
Molecule B may be synthesised in a number of ways, including
1. Reaction of methacrolein with isopropyl magnesium bromide in diethyl ether to give 2,4-dimethyl-1-penten-3-ol, followed by oxidation of the alcohol to the ketone using chromic acid, as follows 
2. Bromination of 2,4-dimethyl-3-pentanone in chloroform (with simultaneous loss of HBr) to produce the bromoketone, 2-bromo-2,4-dimethyl-3-pentanone. Treatment of the bromoketone with 1,8-diazabicyclo [5.4.0] undec-7-ene (referred to as DBU for brevity) in dimethylformamide yields the desired molecule B, as follows 
The invention will be further described, by way of illustration, in the following Examples.
GC/GCMS Conditions for analyses in the following Examples:
GC: Hewlett Packard HP 6890 gas chromatograph
Column: HP-5 (crosslinked 5% Phenylmethylsiloxane) 25mxc3x970.2 mm (internal diameter)xc3x970.33 xcexcm (film thickness)
Carrier gas: Hydrogen
Temperature Prog: 50xc2x0 C. (initial oven temperature) to 280xc2x0 C. at a rate of 12xc2x0 C./min
GCMS : Finnigan Ion Trap instrument
GC Column: JandW DB-5MS 30mxc3x970.25 mm (internal diameter)xc3x970.25 xcexcm (film thickness)
GC Carrier Gas: Helium
GC Temperature Prog: 70xc2x0 C. (initial oven temperature), ramp 40xc2x0 C./min to 270xc2x0 C., hold 10 minutes
MS uses an ion trap; 35-450 amu acquisition, 1 scan/second; source pressure 30 mTorr; electron impact 70 eV; positive ion mode.